This invention relates to a novel use of silica-alumina catalysts in the preparation of predominantly linear polyethylenepolyamines from ethyleneamines and alkanolamines.
Heretofore, polyethylenepolyamine compounds such as diethylenetriamine, triethylenetetramine and the higher homologs have been produced by the reaction of an alkyl halide such as ethylene dichloride with an amine such as ammonia or ethylenediamine at elevated temperatures and pressures. Normally, relatively high yields of predominently noncyclic polyethylenepolyamine compounds are obtained from this process with varying yields of heterocyclic amines.
The large amounts of energy required to produce the reactants as well as the difficult separation procedures required to recover the more valuable linear polyethylenepolyamines diminish the usefulness of the ethylene dichloride process. The hydrohalide salts of ammonia and the polyethylenepolyamine products must also undergo difficult and time consuming caustic neutralization to yield the free polyethylenepolyamines.
Another method of producing predominantly linear polyethylenepolyamines is exemplified by U.S. Pat. Nos. 4,316,840 and 4,316,841. These two references disclose a method of contacting a polyalkylenepolyamine such as ethylenediamine with water in the presence of several different catalysts. The suggested catalysts of U.S. Pat. No. 4,316,841 are various metal phosphates including boron phosphate, iron phosphate, zinc phosphate, aluminum phosphate and others. U.S. Pat. No. 4,316,840 discloses the use of various metal sulphates and nitrates as catalysts instead of metal phoshpates.
A third method of producing predominantly linear polyalkylenepolyamines is disclosed in U.S. Pat. Nos. 4,036,881; 4,044,053; 4,103,087 and 4,314,083. These four references describe a method of reacting an alkyleneamine such as ethylenediamine with an alkanolamine such as monoethanolamine. U.S. Pat. Nos. 4,036,881 and 4,044,053 discloses the use of a phosphorus-containing catalyst such as an acidic metal phosphate, phosphoric acid compounds, phosphorous acid compounds, and various other phosphate esters, acids and salts. The preferred catalysts of the disclosures are the acidic metal phosphates including boron phosphate, ferric phosphate and aluminum phosphate. Additionally, the process of '881 yields a relatively lower conversion to linear polyethylenepolyamines when the disclosed catalyst is employed rather than the supported catalyst prepared according to the present invention.
Additional references which describe the alkyleneamine and alkanolamine reaction with a catalyst are U.S. Pat. Nos. 4,103,087 and 4,314,083. U.S. Pat. No. 4,103,087 provides an example of a specific aluminum phosphate catalyst employed for producing heterocyclic product compounds. The use of metal salts of nitrogen and sulfur-containing compounds and their corresponding acids is described in U.S. Pat. No. 4,314,083 to catalyze the reaction between ethylenediamine and monoethanolamine.
U.K. Pat. Nos. 2,090,157; 2,090,158; 2,090,238; 2,090,267 and 2,090,268 all disclose the use of various catalyst supports containing phosphorus compounds for the polymerization of olefins. More particularly, U.K. Pat. No. 2,090,158 claims a chromium compound supported on a silica and metal phosphate combination wherein the support is prepared by impregnating a silica xerogel with aluminum phosphate or boron phosphate and then precipitating aluminum phosphate on the support in the presence of a silica hydrogel. U.K. Pat. No. 2,090,267 describes a catalyst of a chromium compound on a phosphate-containing support, the support of which can be made by phosphating silica. A method of preparing aluminum phosphate gels as supports for olefin polymerization catalysts is disclosed in U.K. Pat. No. 2,090,238. Chromium compounds supported on aluminum phosphate or a phosphate containing support are claimed in U.K. Pat. No. 2,090,268.